A mounting mechanism is used when performing a processing on an object such as a wafer. The mounting mechanism includes: a mounting table for mounting thereon the object; a plurality of elevating pins protrusible above and below a mounting surface of the mounting table; and a plurality of air flow paths opened at plural locations on the mounting surface to fixedly vacuum-chuck the object onto the mounting surface of the mounting table. By performing a vacuum pumping through the plurality of air flow paths with a vacuum pump, the object is fixedly vacuum-chucked on the mounting surface of the mounting table.
When performing a preset processing on the object, a transfer mechanism transfers the object to the mounting table and hands it over to the plurality of elevating pins protruded from the mounting surface. Then, the transfer mechanism retreats from the mounting table. Meantime, in the mounting mechanism, the plurality of elevating pins is moved down below the mounting surface of the mounting table so that the object is loaded on the mounting surface. Once the object is loaded and fixedly vacuum-chuck onto the mounting surface, the object is hermetically attracted and held by the mounting surface. After completing the processing on the object, the processed object is unloaded from the mounting table. The vacuum-chucking for the unloading process of the object onto the mounting table is released, and the plurality elevating pins are raised from the mounting table to lift the processed object therefrom. The transfer mechanism then receives the processed object lifted by the elevating pins to finally unload the object from the mounting table.
Further, disclosed in, for example, Japanese Patent Laid-open Application No. S63-142653 (Patent Reference 1) is a prober having a mounting mechanism (chuck) different from the type of the above-described mounting mechanism. The prober includes a chuck having a suction port in communication with a vacuum pump, wherein the air inlet of the chuck is slantingly installed toward the side of a loader and a blower is connected to the suction port via a changeover switch. In the prober having this configuration, air is blown through the suction port by the blower when unloading a wafer from the chuck. Accordingly, the wafer can be rapidly transferred from the chuck to the loader side by the air force generated in the air flow direction.
Moreover, disclosed in Japanese Utility Model Laid-open No. S50-127097 (Patent Reference 2) is a suctioning and vacuuming apparatus for a vacuum table. In this apparatus, an exhaust side and a suction side of a pump is connected with a chamber of the vacuum table via a direction changeover valve. By switching over the direction changeover valve, the chamber is made to communicate with either one of the exhaust side and the suction side of the pump selectively. When unloading a wafer W from the vacuum table, the vacuum table is configured to communicate with the exhaust side of the pump by means of controlling the direction changeover valve.
With regard to the conventional mounting mechanism having the elevating pins, however, the object is vacuum suctioned by the mounting surface and firmly adhered thereto. Thus, in order not to incur a depressurized state when unloading the processed object from the mounting surface of the mounting table, the object needs to be lifted up by the elevating pins at a very low speed while concurrently supplying exterior air between the object and the mounting surface gradually. Therefore, unloading the processed object takes a long time. For example, about 6 to 7 seconds are required to lift the processed object from the mounting surface to a transfer location. If the unloading of the object is quickly carried out rather quickly, a depressurized state may still persist between the object and the mounting table while the object is pushed up by elevating the plurality of the elevating pins; then, the central portion of the object would be lifted up earlier than the periphery thereof. As a result, the object would be bent greatly, which in turn may damage in the breakage of the wafer W. As the object increases in size and decreases in thickness, the likelihood of the object being damaged increases. In case of the apparatuses disclosed in Patent References 1 and 2, such problems of the mounting mechanism having the elevating pins do not exist since they do not have elevating pins.